I have invented certain new and useful improvements for pre-fabricated assemblies of threaded bars, for which Letter Patent were granted on Feb. 23, 2016, U.S. Pat. No. 9,267,287 (Bongiorno '287). These improvement may also be adapted to improve the prefabrication system described in U.S. Pat. Nos. 8,381,479 and 8,375,678 (Ferrer '479 and Ferrer '678). A recitation of the relevant portions of Bongiorno '287, Ferrer '479 and Ferrer '678 are not provided herein since such relevant portions are incorporated by reference herein.
Bongiorno '287 describes a prefabricated assembly of threaded reinforcing bars wherein certain embodiments include, but are not limited to, the use of at least one internally threaded sleeve in the cage frame assembly. Other embodiments utilize smooth bore sleeves with locking means to hold the bars against the sleeves.
In some embodiments of Bongiorno '287, the internally threaded sleeves are first attached to the cage frame assembly and then longitudinal bars are threaded, or rotated, through the internally threaded sleeves (as shown in Prior Art, refer to FIG. 1A). In other embodiments, the internally threaded sleeves are first threaded, or rotated, onto the longitudinal bars and then the internally threaded sleeves with the bars in them are attached to the cage frame assembly (as shown in Prior Art, refer to FIG. 1C). In yet other embodiments, the internally threaded sleeves are split, or openable, type sleeves. In such embodiments, the split sleeves are first attached to the cage frame assembly and then longitudinal bars are placed into, or against, them, with the external threading of the bars aligned with the internal threading of the split sleeve (as shown in Prior Art. refer to FIG. 1B). Then the split sleeves are closed, or otherwise secured.
One of the objects and advantages of Bongiorno '287 is to provide a self-supporting prefabricated reinforcement cage that is strong, stiff and stable when installed in a vertical orientation. Those skilled in the art will recognize the importance of having the ability to maintain a rigid connection between at least some of the reinforcing bars and the upper cage frame of Bongiorno '287, or upper template of Ferrer '479 and Ferrer '678, as the case may be.
Referring to Prior Art FIGS. 2A and 2B, such rigidity is achieved by providing rotational and axial restraint between at least some of the reinforcing bars and the cage frames, or templates, as the case may be. While such restraint can be provided by torqueing opposing lock nuts against the top and bottom faces of a cage frame or template, those skilled in the art will recognize that in an application where the bars are to be rotated for connection to other bars, such clamping action between the opposing lock nuts may oppose such rotation. Alternatively, the bar rotation may cause a loosening of the clamping action between the opposing lock nuts, thus reducing their ability to provide the desired rotational and axial restraint. Restoring that rigidity may require a worker to ascend the reinforcing cage to restore the locks at the upper retainer, which can be at a considerable elevation and thus poses a safety issue. The internally threaded sleeves of Bongiorno '287 allow for free rotation of the bars, while maintaining adequate rotational and axial restraint between the bars and cage frames.
Although each of the above referenced embodiments of Bongiorno '287 achieves the above stated objective of providing rigidity to a reinforcing retainers, such as a cage frame or flat template cage, those skilled in the art will recognize that each of those embodiments has an impact on the time and effort required to fabricate the assembly. For example, installing the longitudinal bars by threading, or spinning, them into the internally threaded sleeves requires temporary supports for alignment and the use of rotating tools or substantial manual effort, which can add time and cost to the fabrication process. This embodiment also may require more space allocation in the shop or in the field for fabrication. Other embodiments may require, for example, temporarily holding the longitudinal bars and respective internally threaded sleeves in position against the cage frames while attachment is made.